I think no matter what world you're building, whether that be a science fiction world on this planet or another one, or a fantasy world, there are social classes. Your main character falls into one of them, and there's usually some jostling between these classes as the story progresses.
Whenever I'm thinking of what kind of social classes I'd like in my books, I think of the movie In Time. Yeah, it has Justin Timberlake, which isn't as bad as you might think. *wink*
It wasn't my favorite movie ever, but it set up the social classes really well. There's part of the movie where Justin Timberlake -- Salas -- moves up the social ladder, so to speak. And it's very literal, as he passes through the different "time zones" of the world.
I love thinking about that part of In Time, and it helps me build my social classes in a way that makes sense to A) the plot, B) the main character, and C) the government I've already established.
Some questions to ask yourself:
- What class is my main character in now?
- How did they get there?
- How can they advance? Is that even possible? What would have to happen? (In the movie In Time, Salas only advances through the time zones because someone died -- oh, and he's been accused of causing that death. So yeah.)
- What are the advantages of each social class? The disadvantages?
- Why would someone want to be in a position of power in this world?
- Why would they want to remain in their lower class?
- What are the consequences associated with moving classes? (Loss of family connections, loss of friendships, loss of freedoms, etc.)
I find social classes fascinating, because you don't have to be writing speculative fiction to find them. You probably have them at your office, in your schools, or down the street in your own neighborhoods.
That's why the social classes in your novel need to be well developed -- because they have the power to truly resonate with readers.
What questions do you ask yourself about social classes when building your story world?